Article : Naturally Colorful
Why synthetic colours are used instead of natural colours?
Normally, the permitted colours are more able to withstand rigorous processing systems, high temperatures and extreme pHs which natural colours cannot. Synthetic colours also tend to be more economical and not much affect on finished-product flavor. Even some synthetic colours are derived from colorful fruits and vegetables which are often the healthiest part of the product. With this, a product often provides unique opportunities to market potential nutraceutical benefits.

Article : Colors Au Naturel

What are the disadvantages of natural colours?
Commonly, natural colours are more expensive. Before extracting colours from natural sources like vegetables and fruits, manufacturing, concentration and purification steps are needed. Only limited pigment can be obtained in a given volume.